Physics Unit6: Work and Energy - 题库网 (tiku.one)

1#

What is the correct unit of a7nc +oe yug29work expressed in SI units?

A. $kg m/s^2$

B. $kg m^{2}/s$

C. $kg m^{2}/s^2$

D. $kg^2 m/s^2$

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on a system if there is n.nly:pk sl p5(5y fxn50(hgv.qjm s f7o motion?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

C. No, since a system which is not moving has no energy.

D. No, because of the way work is defined.

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard against + v/s7e bgee9s2gq,ela stationary brick wall, the amount of work you db,/+ ggeev 9eeql2ss7o

A. doubles.

B. is cut in half.

C. remains constant but non-zero.

D. remains constant at zero.

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4#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 50-N object was lifted 2.0 m vertically and is being heliu jvcg07bvr*jkwcr;1u r4a2h5iql t y+/ 1j8d there. How much work is being done in hywqjc4au t+ k5b jrl; 27rhv rjg11/ *u0cvi8iolding the box in this position?

A. more than 100 J

B. 100 J

C. less than 100 J, but more than 0 J

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horizontallybez +(2zgqe tt nv 1ovv*tz86k7u)a/e forward at a constant velocity carrying a 10-N object, /*6t7tgbko 8euqnae v )evz(z1v2z t +the amount of work you do is

A. more than 50 J.

B. equal to 50 J.

C. less than 50 J, but more than 0 J.

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted vertically 3.0 m then retmlp+w k v/b2ytw89m)cvg* zw:urned to its original position. If b)9tyw / v8vmpmcl +wwg*: z2kthe total weight is 30 N, how much work was done?

A. $45 \; J$

B. $90 \; J$

C. $180 \; J$

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal forceaewb v 6izz 7bzzjv-q +5+1wn9w5:yiu acting on an object do work on the object?

A. Yes, since a force acts and the object moves, and work is force times distance.

B. Yes, since it takes energy to turn an object.

C. No, because the object has constant speed.

D. No, because the force and the displacement of the object are perpendicular.

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up. Compare the sig7u1r s1zsnw2p4d q,yotm w2*en of the work done by gravity while the ball goes up with the sign of the work done by gr,tprsw4o 72z1 e2 1yqn udmws*avity while it goes down.

A. Work is + on the way up and + on the way down.

B. Work is + on the way up and - on the way down.

C. Work is - on the way up and + on the way down.

D. Work is - on the way up and - on the way down.

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, on a Force versus position yacu/z:eff dih:2o19 -hcy *)fhhnk * (F vs. x) graph, represents nz* a/hc fy9khudhi*f h:)-2y1e :foc

A. work.

B. kinetic energy.

C. power.

D. potential energy.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

On a plot of Force versus posi1*jc,)/mp f3shscgyup4j 5 vbtion (F vs. x), what represents the work done by the force 4hpscu *y3 jfvg1smb,)/j cp5F?

A. the slope of the curve

B. the length of the curve

C. the area under the curve

D. the product of the maximum force times the maximum x

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity $\frac{1}{2} \; mv^2$ is

A. the kinetic energy of the object.

B. the potential energy of the object.

C. the work done on the object by the force.

D. the power supplied to the object by the force.

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is positive, then d e5j.5cxyfzw;5 xfo 48qzgc ;the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an objrvb)0p8 q d47anib4p rect is negative, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is zero, then the object'h)j.e:v q. b;y6r mexys kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice as much as a cmz c5b,) yke7 qri;un7ar, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy compared to t5zqek)7 mc rb7iy;n,u hat of the car?

A. All that can be said is that the truck has more kinetic energy.

B. The truck has twice the kinetic energy of the car.

C. The truck has 4 times the kinetic energy of the car.

D. The truck has 8 times the kinetic energy of the car.

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as car K, and gxa7(9e5w l +0fp:dz a+rm+y i r6k5,geldr qncar J has half the mass of car K. The kinetic energy of car J, compared to ca(5y+lpf: egixza0w7n59,ar+de gdlrq 6 kmr+r K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounceseeep5 ;ik.x0 jr yfm9n-snp.1 back with half of its original speed. What is the ratio of the final.sp-k 9enri0me ny;5 p1.fxj e kinetic energy to the initial kinetic energy?

A. \frac{1}{2} \;

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a speed of 3 m/s anqgv/sbk : mp;7d a pebble is moving at a speed of 5 m/s. If both objects have the same kinetic energy, what is the k:mb/q;s7v gpratio of the brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-kg mass is moving with sv* 6 gg3b;bnbr(5lufl5)yai lpeed 4.0 m/s. Both objects encounter the sf5;u*vnl) i 6b5 g3g yl(brablame constant braking force, and are brought to rest. Which object travels the greater distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes of your car in a panic, and skid tzb +gnx-f8j w.a8*vi s:in,ma certain distance on a straight, level road. If you had been traveling twice as fast, wha8:8snx *+,v jmfbziintg -.awt distance would the car have skidded, under the same conditions?

A. It would have skidded 4 times farther.

B. It would have skidded twice as far.

C. It would have skidded 1.4 times farther.

D. It is impossible to tell from the information given.

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A planet of constant mass orbits the Sun in an elliptical ypd /j,l*m 8a1vj.fkw g85ymoorbit. Neglecting any fr/1k md8 ,oav.m fypjyl*5wg 8jiction effects, what happens to the planet's kinetic energy?

A. It remains constant.

B. It increases continually.

C. It decreases continually.

D. It increases when the planet approaches the Sun, and decreases when it moves farther away.

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22#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the work-energy principl7mtk )(p el oayx*s,y5e.

该题自我估分: (必填) (满分:1.0分)

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23#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity mgy is

A. the kinetic energy of the object.

B. the gravitational potential energy of the object.

C. the work done on the object by the force.

D. the power supplied to the object by the force.

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity $\frac{1}{2} \; kx^2$ is

A. the kinetic energy of the object.

B. the elastic potential energy of the object.

C. the work done on the object by the force.

D. the power supplied to the object by the force.

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Is it possible for a system to hav+x,7 evsyul:z :w1(plkaq4k ae negative potential energy?

A. Yes, as long as the total energy is positive.

B. Yes, since the choice of the zero of potential energy is arbitrary.

C. No, because the kinetic energy of a system must equal its potential energy.

D. No, because this would have no physical meaning.

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a heighif dslxi8nj+4 fg ,;t,t h above the ground. A second object with four times the mass of the first if released fs +jn ,gd;fi8lt,ix4from the same height. The potential energy of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached to the end of a spring causes it to st+1pd njqm-lttl0,kow* 0l(d eretch 5.0 cm. If another 0.200-kg mtp 0 q(dnl1l,*-ek odmt+jw0 lass is added to the spring, the potential energy of the spring will be

A. the same.

B. twice as much.

C. 3 times as much.

D. 4 times as much.

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The total mechanical energy of a syb1aq,.qh 6gax5;l gemv4r2 fhstem

A. is equally divided between kinetic energy and potential energy.

B. is either all kinetic energy or all potential energy, at any one instant.

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a trpi:q zs q-3nn+ee. Compare its kinetic energy K, to its potential energy U.zqiqpn3n-+ :s

A. K increases and U decreases.

B. K decreases and U decreases.

C. K increases and U increases.

D. K decreases and U increases.

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30#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Describe the energy of a car ju c.fbmstjz(/1)p ,fdriving up a hill.

A. entirely kinetic

B. entirely potential

C. both kinetic and potential

D. gravitational

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31#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A lightweight object and a very heavy ik;gmetu agw7 kjm1413c: r u5object are sliding with equal speeds along a level frictionless surface. They both slide up the sa3c:majkgr1u5 4getkw;7m 1i u me frictionless hill. Which rises to a greater height?

A. The heavy object, because it has greater kinetic energy.

B. The lightweight object, because it weighs less.

C. They both slide to the same height.

D. cannot be determined from the information given

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32#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Consider two masses vzzo;,c 0vl m5$m_{1}$ and $m_{2}$ at the top of two frictionless inclined planes. Both masses start from rest at the same height. However, the plane on which $m_{1}$ sits is at an angle of $30^{\circ}$ with the horizontal, while the plane on which $m_{2}$ sits is at $60^{\circ}$. If the masses are released, which is going faster at the bottom of its plane?

A. $m_{1}$

B. $m_{2}$

C. They both are going the same speed.

D. cannot be determined without knowing the masses

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33#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the principle of conserrhmhw+(y sc8xdtq*i3c602e uvation of mechanical energy for conservative forces*qccihm3s+2 dtwyureh0 8 x6(.

该题自我估分: (必填) (满分:1.0分)

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34#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball falls from the top of a building,2o9 t.vkbf( qv through the air (air friction is present), to the ground below. How 9b2fkqov.vt(does the kinetic energy (K) just before striking the ground compare to the potential energy (U) at the top of the building?

A. K is equal to U.

B. K is greater than U.

C. K is less than U.

D. It is impossible to tell.

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance asflq4 v9:,e + ktassc9 6b)oaynd gains 30 J of kinetic energy. Do not ignore air re :9)ty+l9a sbfoeckssv6a q,4sistance. How much gravitational potential energy did the ball lose?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and loses 30 J mbk;h-s;-p-/vxayf a of gravitational potential energy. Do not ignore air resistance. How much kinetic en vfax; ksy ---;b/mpahergy did the ball gain?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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37#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of conservation ofaj5:c*x bh gz gfegp)5mxv-9+ energy.

该题自我估分: (必填) (满分:1.0分)

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38#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity Fd/t is:syn nn()*col

A. the kinetic energy of the object.

B. the potential energy of the object.

C. the work done on the object by the force.

D. the power supplied to the object by the force.

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39#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the correct unit of power ex ,(p(j pmf- ploifc:l+pressed in SI units?

A. $kg m/s^2$

B. $kg m^{2}/s^2$

C. $kg m^{2}/s^3$

D. $kg^2 m/s^2$

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which g:a 36w ;7xswqhh lgbsi+1ld 8is not a unit of power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the work in one-third the ti8 0hjez-exm*j)8 wybkme. To do so, your power ou*jk- zew8 jm)h8yx0e btput must have been

A. the same as yesterday's power output.

B. one-third of yesterday's power output.

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a constant accelerr o4zj4g4 h:ndation, the car's engine must

A. maintain a constant power output.

B. develop ever-decreasing power.

C. develop ever-increasing power.

D. maintain a constant turning speed.

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43#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is lifted vertically 2.0 m and t qa y3wq7*mk/held there. If the object weighs 90 N, how much work was done in liftq* tm3ky/ w7qaing it?

A. $360 \; J$

B. $180 \; J$

C. $90 \; J$

D. $0 \; J$

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You lift a 10-N physics book up in the aiqyd3 i30 xesn4r a distance of 1.0 m, at a constant velocity of 0.50 m/s. 3sxiqe3yd0 4n What is the work done by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a p 5rj1in *ji/gconstant force of 5500 N for a distancegjijn51 ri*p/ of 50.0 m. What is the work done by the 5500 N force?

A. $2.75 \times 10^{5} \; J$

B. $-2.45 \times 10^{5} \; J$

C. $3.00 \times 10^{4} \; J$

D. $-5.20 \times 10^{5} \; J$

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46#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N for a d6mwzc 39fggo5istance of 50.0 m. What is the93g 5wc fgmoz6 work done by the weight of the elevator?

A. $2.75 \times 10^{5} \; J$

B. $-2.45 \times 10^{5} \; J$

C. $3.00 \times 10^{4} \; J$

D. $-5.20 \times 10^{5} \; J$

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pro+ dqrm ,p ozqc33(e,ulled upward with a constant force of 5500 N for a distance of 50.0 m. Whqdomr er,3p ,qo (3zc+at is the net work done on the elevator?

A. $2.75 \times 10^{5} \; J$

B. $-2.45 \times 10^{5} \; J$

C. $3.00 \times 10^{4} \; J$

D. $-5.20 \times 10^{5} \; J$

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled 6.0 m up alor4m8gm sksg67mm j8 i-ng a $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

A. $-11 \; J$

B. $-1.1 \times 10^{2} \; J$

C. $-1.4 \times 10^{2} \; J$

D. $-1.8 \times 10^{2} \; J$

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit y8g(t:ykt f (bm* 9iexslides 8.0 m down a ramp, inclined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

B. $-157 \; J + 78.4 \; J$

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his littl6gl0w6z6bu v re/ 5*u apavcw5e sister Sarah in a sled on an icy surface (assume no frictiwve5u6cwlapv06raz/ g 65*u bon), with a force of 60.0 N at an angle of $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

A. $185 \; J$

B. $433 \; J$

C. $575 \; J$

D. $720 \; J$

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the dir *8k7w,xtcx hl psg4ftjr*u68 ection of the force. The graph in Fig. 6-1 shows the fx8pkx t clgft8 * 6h4r,w7jus*orce versus the object's position. Find the work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The grap,-vxfri+ j u5:5gt ms4zi:aq ;fudt;mh in Fig. 6-1 shows the force versus the oufis+rgx5qz -; m4: tv;5jt m,da:uf ibject's position. Find the work done when the object moves from 2.0 to 4.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction 49:mob * ukg gytq yq.pgcx-; 92hxlq-of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done-y ugcxxqqg.q tb:;l9mokh*y9 2 4 -pg when the object moves from 4.0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object9dqv6xh:y6)cam0a r9 ixo2 x .1.udz fai j2xw in the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 0 to 6.0 jcyv2x)d:axir6 6 da0 9awu.xi ozq 29m1 x.hfm.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (in av.s(ylnm9gg- )apay8ejy.( itially at rest) across a 19s gayy g( (yn.pjl )m.v8-aea0 m level surface. What is the final kinetic energy of the cart?

A. $1.0 \times 10^{3} \; J$

B. $2.0 \times 10^{3} \; J$

C. $2.7 \times 10^{3} \; J$

D. $4.0 \times 10^{3} \; J$

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (imyjyh+.ep -wntj )ko8,3pq;- 2 ibvru nitially at rest) across a 10 m leverojwpyimhpq3t +k2).- un- ;v,be8yj l surface. What is the final speed of the cart?

A. 73 m/s

B. 36 m/s

C. 8.5 m/s

D. 6.0 m/s

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass is moving with a speed of 5*bko)d ub0hvp 4b7ko2.0 m/s. How much work is required to stob4u bpd7kbohk *0v)2op the mass?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a c /)fa-peh1l7+q -qxbkbpp+e j ar initially moving at 25 m/s, what distance is required to stop a car moving at 50 m/s under the same conx1pph+bb7f p e/kaq-)- q ej+ldition?

A. $50 \; m$

B. $100 \; m$

C. $200 \; m$

D. $400 \; m$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring-driven dart gun propels a 10-g dart. It is sc rzm;y;31w gcocked by exerting a force of 20 N over a distance of 5.0 cm. With what speed will wrz;3g1m; ysc the dart leave the gun, assuming the spring has negligible mass?

A. 10 m/s

B. 14 m/s

C. 17 m/s

D. 20 m/s

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 100-N force has a horizontal component of 80 N and a ver9xoh2 dhqw6op:0yu u iqmu0 59tical component of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m hor:0q6whh y 2quo o099mx5udu piizontally along the floor. What is the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally int(rwfbe-ltn l4m*g5u 1o a bale of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force acting on the arrorn um4glbfet (w*51-l w?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 m above amz4su1g ib 1j855apd i floor to a height of 13.0 m above the floor. What is the change in gravitational potential zp 58 1asdj ibug4i51menergy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plane. The plane is 4.0 m long and rise bz4o;0m4j eo9aka,hks 2.0 m. If the plane is ab04ak4j,zo e 9;mokhfrictionless, how much work was done by the push?

A. $1600 \; J$

B. $800 \; J$

C. $400 \; J$

D. $100 \; J$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass, hung onto a spring, causes the spring to stretch *n-n 0uo:(o)+vnnswct )x yvk 2.0 cm. What is the spring constant? uv(xt-csoo kwn)n nn0* +:v)y

A. $4.9 \times 10^{3} \; N/m$

B. $5.0 \times 10^{3} \; N/m$

C. 20 N/m

D. 2.0 N/m

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring is characterized i 9k6m29qflvr mc.b z7oo4j+l by a spring constant of 60 N/m. How much potential energy does it store, when stretched by 1.0 cm?4m .7fi 9 kl2o9zo l+cbrqmj6v

A. $3.0 \times 10^{-3} \; J$

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required te48rxgk :atq) ygj6i ) g;xnt:o compress an initially uncompressed spring with a spri:gke)nitx aq4 g g)jt:8xry6;ng constant of 25 N/m by 10 cm.

A. $0.10 \; J$

B. $0.13 \; J$

C. $0.17 \; J$

D. $0.25 \; J$

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is required to stretch a spring of spring consbnsc/ wa, umx*6vrr7+tant 40 N/m from x = 0.20 rwc arvum+6 x/s,7 bn*m to 0.25 m? (Assume the unstretched position is at x = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constant of 15 N/m is initia-wqvxqe*/ qpk0eb+ajj8x6 , clly compressed by 3.0 cm. How much work is required to compress the spring an additional 4.-*q68,abw k/e jqpjxexc0v+ q0 cm?

A. $0.0068 \; J$

B. $0.012 \; J$

C. $0.024 \; J$

D. $0.030 \; J$

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69#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50-m high slope. What is thawz p+ :5/t*zdq7tqwlxgt /a8zmu97 ge speed of the slier on reaching thelgwqtwt/7zz8+z *9tua7 xq gdp m:5a / bottom of the slope? (Neglect friction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top of a hi rh,8myd8r+rakm/)e z ll with an initial speed of 4.0 m/s. Neglectin+8 zmkhdar)y ,8m /rreg friction, how fast will she be moving after dropping 10 m in elevation?

A. 7.3 m/s

B. 15 m/s

C. 49 m/s

D. 196 m/s

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object slides down a frict ia)aal:xnr4 r-30 zhtionless inclined plane. At the bottom, it has a speed of 9.80 m/s. What is the veh04i a -zx 3a)ltnr:arrtical height of the plane?

A. $19.6 \; m$

B. $9.80 \; m$

C. $4.90 \; m$

D. $2.45 \; m$

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72#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1.0-kg ball falls to the f n0m,qw0 +aojo1*i ugbloor. When it is 0.70 m above the floor, its potential energy exactly equals its kinetic energy. Howmqow0 g 1o j0a+n,*ubi fast is it moving?

A. 3.7 m/s

B. 6.9 m/s

C. 14 m/s

D. 45 m/s

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73#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A toy rocket, weighing 10 N, blasts straight up from ground level with a kiq +ih)xnsog94netic energy of 40 J. At the exact t) i4+xgs9on qhop of its trajectory, its total mechanical energy is 140 J. To what vertical height does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of massqd3:61jkueo()ld2ef 1gec az m leaves the ground with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To ojuzdd 16a :3e2cqk) 1fe(g lewhat vertical height, relative to its launch point, did it rise?

A. $\frac{220}{mg} \; m$

B. $\frac{120}{mg} \; m$

C. $\frac{100}{mg} \; m$

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from rest at a point 45 m above the bottom of a dip (wt;mh7p/ g, stju77mzSee Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottomzu7g 7;tmwt/7 shpm,j of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.0 m/s at a point 45 m above t/d2pw6r8:feua iu0 b.3jyc rlhe bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed f8ibruay6:3pl uw 0d.e/ r2cjof the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a point 30 m above the bottom -ab1i4iq s-crnd os:/cru6e 5of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be thqcibori5r/64-ss u-cnade :1 e speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the ball at the otw1qzo,y :au4elqh*-)t1b.uq opb*bottom of its swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 cm is pula5)9nzng etxpa8m s 33 qabapwi*4m93led 30 cm away from the vertical axis and released from rest. What will be its speed at the bottom of 8ip )n3t95ep wmam3a39x gna zabs 4q*its swing?

A. 0.50 m/s

B. 0.79 m/s

C. 1.2 m/s

D. 1.4 m/s

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car moving at 25 m/s hits an im)p-nkut1* vrnitially uncompressed horizontal spring with spring cons-kv u1n pt*m)rtant of $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling at 22 m/s, slows down her 2000 kg carzvi99,ymv+mjj2*.l n1r0e8 jjxd.u w0r qb qi to stop for a red light. x i irvm2q 8uq0lyzevj9r+ 0wj*.n,j9bm1d.j What work is done by the friction force against the wheels?

A. $-2.2 \times 10^{4} \; J$

B. $-4.4 \times 10^{4} \; J$

C. $-4.84 \times 10^{5} \; J$

D. $-9.68 \times 10^{5} \; J$

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kg object and a horizontal wla0xobgk 9lg1 p5aeng1a)2qg. 3c k-surface is 50.0 N. If the initial speed of thealx1b5e2g0 .gg-oq kp9lcnk 3)1 agaw object is 25.0 m/s, what distance will it slide before coming to a stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is moving on a rough, level surface. It has 24 J ;+).ifowmqmm )apsz0of kinetic energy. The friction force on it isfm+m;qo 0s)zwa)p. m i a constant 0.50 N. How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-kg mass on a level surface. Th1otc,f) kc, 9fyqj y6ne coefficient of kinetic friction between the mass and tq)o ,k n1tj,9cy fyf6che surface is 0.20. If the mass is moved a distance of 10 m, what is the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the topvq2f1ho7g4 *clgn05z/ tbqm 8j kpuf* of a 50-m high slope. If the work done by frictiv2h 0 *lg7zcu 5mj/ *k4b8qfqg1fnopton is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

A. 17 m/s

B. 24 m/s

C. 34 m/s

D. 31 m/s

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inclined plane. The plane is 4.0 m long and ris:,kgh.(1 ow up 4fvolkes 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What was the magnitude of the average friction forc( gvo1w4l okkp.:hu,f e on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rest at the top of a plane inclined at ti8jx8k uzte8)9a3ox 20e above horizontal. The coefficient of kinetijxto3 ez )9uk t888axic friction between the mass and the plane is 0.20. What will be the speed of the mass after sliding 4.0 m along the plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from a height of lef7 ak8m k46l10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air friction acts on 87lfl keak4m 6it as it falls?

A. $22.5 \; N$

B. $75.0 \; N$

C. $225 \; N$

D. $293 \; N$

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using energy when he runs up a fli 0llf*j.6 y3hmi.lth dght of stairs 10.0-m t0l m*djyihlf36.l.hhigh, in
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an obcs2vd(,;qhkl,o0l7 r tl- tjbject with a constant velocity of 5.0 m/s. What power must be delivered to the object by th c jtl,;ol v2bs7(kt0qdr- h,le force?

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of ener5 s+qr5y-0gt 6gclxmw gy are used by a 1.0 hp motor that runs for 1.0 hr? (1 hpgsw+m qy5xtg-rc 05l6 = 746 W)

A. $3.6 \times 10^{3} \; J$

B. $2.7 \times 10^{6} \; J$

C. $4.5 \times 10^{4} \; J$

D. $4.8 \; J$

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94#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A cyclist does work at the rate of 500 W while riding. How mi*sfw6vyznb j: gz72 +uch force does her foot push with when shez ws7yv b2if+ g6zn:j* is traveling at 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates from 0 to 25t x-5 oz1-uiiw ,qwsr4 m/s in 7.0 s. What is the average power dwirzq 5s-w o ,u4-tx1ielivered by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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